Technical Field
The present invention relates to adsorbents for wastewater treatment. More specifically, the present invention relates to activated carbon composites as high-capacity adsorbents for removal of mercury and other toxic metals from wastewater and any aqueous media.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.
The development of industry has led to severe problems of water pollution which is considered a problem due to its increasing toxic threat to humans and the environment. It is imperative for wastewater treatment for the removal of pollutants to provide good quality water. Organic and inorganic pollutants have been reported to thrive in such waste waters. Among these, metal pollutants are not biodegradable, and persist in the environment for a long time. Such pollutants are toxic, pose a serious threat to the environment. Among toxic inorganic or metal ions include arsenic, cadmium, selenium, antimony, lead, chromium and mercury.
Different techniques for wastewater treatment are available, including reverse osmosis, ion exchange, electrodialysis, and electrolysis. However, such methods have their own limitations such as low efficiency, sensitive operating conditions and further the disposal is a costly affair. Continuous increase in the variety, amount and complexity of the toxic pollutants has made the conventional wastewater treatment methods ineffective. Alternative technology is adsorption where adsorbents are used to remove the pollutants. Thus, it is required to have low cost and efficient adsorbents for large-scale use in water treatment with regenerability.
Carbon materials like activated carbon, carbon nanotubes and graphene can be used as adsorbents for the advanced treatment of wastewater. These carbon materials can be used for the removal of organic and inorganic pollutants from aqueous media. Other materials that can also be used as adsorbents include iron oxide, manganese oxide (birnessite), zeolites, titania, clay. Among these different types of adsorbents, activated carbon is of a considerably lower cost.
However, activated carbon can suffer from either low adsorption efficiency or pollutants easily leaching away from the surface after adsorption. Several methods have been reported to enhance its activity. For example, activated carbon was loaded with some metal oxides and nanoparticles. The presence of functional groups on the adsorbent surface reduces the binding energy, while increasing the uptake kinetics at low coverage, thus enhance the efficiency of the adsorbent.
Accordingly, there remains a need for novel adsorbent materials for wastewater treatment that can advantageously combine properties such as high surface area, high adsorption capacity and regenerability.